PORTLAND, Maine — Signaling support for a buffer zone recently created in Portland to push anti-abortion protesters away from the city’s Planned Parenthood offices, the Maine attorney general’s office on Thursday night announced it will add its voice to a U.S. Supreme Court case on the issue.

In early 2014, the country’s highest court is expected to hear arguments in the case of McCullen vs. Coakley, in which 35-foot buffer zones designed to keep protesters away from the front doors of abortion clinics statewide in Massachusetts is being challenged as an infringement on the demonstrators’ constitutionally protected rights to free speech.

The city of Portland and members of the group Pro-Life Missionaries of Maine are monitoring the case, as the Supreme Court’s decision will set a precedent that will be felt locally. On Monday, the City Council unanimously approved a 39-foot buffer zone to push back protesters who have been gathering outside the Congress Street Planned Parenthood offices weekly.

Patients of the clinic told police and city officials that they felt “intimidated and harassed” by what they described as a gantlet of demonstrators lining the sidewalk path to the Planned Parenthood door. Protesters countered that their behavior was being blown out of proportion, that the lack of any arrests from the regular demonstrations shows that they’ve been peaceful and law-abiding, and that the activity is protected speech as defined by the First Amendment.

On Thursday night, Maine Attorney General Janet Mills, a Democrat, announced that her office has signed onto an amicus brief arguing that states “must have flexibility to protect access to healthcare facilities, that the Massachusetts buffer-zone law is a valid ‘time-place-manner’ restriction that reasonably addresses the distinctive history of congestion at healthcare facilities and that the buffer-zone law is content neutral.”

The brief is being circulated by New York Attorney General Eric Schneiderman, according to Mills’ office.

“A woman has a right to access health care without fear and harassment,” Mills said in a statement. “The Massachusetts statute simply seeks to enhance public safety near reproductive healthcare facilities by establishing a clear and valid framework for any protected free speech activities that others seek to exercise in the vicinity. The statute was upheld upon appeal and I believe the Supreme Court will find this statute to be constitutional.”

The weekly anti-abortion protests in Portland, which began last fall, initially triggered a counter-protest last winter organized by area businessman Mike Fink, and the early January protest duel over abortion rights attracted widespread media attention.

Fink, a longtime buffer zone advocate, blamed the regular demonstrations for driving foot traffic away from his nearby restaurant, which he closed in August.

The nonprofit Planned Parenthood has been a target of anti-abortion activists nationwide because of the organization’s advocacy for reproductive rights. Some congressional conservatives have similarly fought to eliminate federal funding for the organization over the years because it provides information about — and in some cases performs — abortions.